Gears
Thread Starter
Staging Lane
Joined: Jun 2006
Posts: 86
Likes: 0
Gears I have a 98 z28 A4 with the 2.73s and i was wondering how much would i feel a difference if i go to a 3.73 gear. how much would it change bottom end pull and 1/4 mile time? what would be the best gear choice also?
TECH Addict
Joined: Jun 2005
Posts: 2,660
Likes: 14
From: England
There is no generic "best" gear choice. It all depends on individuals and their goals.
However you'll find most will say 3.73, with a few opting for 4.10 or 3.42.
The biggest thing to understand is what affect gearing has on a auto car, also the limitations of the auto tranny.
There are many people running 2.73's in the low 11's and a few in the 10's.
3.73's will allow the car to accelarate quicker, but at a cost of terminal speed. This means at the red line in each gear you will have a lower mph. Balancing this with what you want from the car is important.
The tranny should only be used in 3rd or D when racing as WOT kickdown and shifts into/from 4th (OD) are bad for it. This means your top speed is somewhat limited to the rev limit in 3rd. This means on an otherwise stock setup you will be limited to about 120mph in 3rd. This might be ok for some, but not for others.
Future mods may also dictate what gearing is needed, aftermarket cams and bolt ons will allow you to raise the rev limiter and allower higher speeds in gear, a cam may require different gearing.
Your best bet is leave the rear alone until you know what you want. A stall would be a much better bet as it will help to overcome gearing due to a thing called shift extension and torque multiplication. I'd go for no less than a 3600rpm stall.
Also remember the stick Fbody rear is pretty weak, if you're serious it might be worth waiting until you upgrade the rear before you worry about gearing.
BTW - theres a link to gear calculator in my sig, you may find it helpful in deciding waht ratio is best for your setup/intentions.
However you'll find most will say 3.73, with a few opting for 4.10 or 3.42.
The biggest thing to understand is what affect gearing has on a auto car, also the limitations of the auto tranny.
There are many people running 2.73's in the low 11's and a few in the 10's.
3.73's will allow the car to accelarate quicker, but at a cost of terminal speed. This means at the red line in each gear you will have a lower mph. Balancing this with what you want from the car is important.
The tranny should only be used in 3rd or D when racing as WOT kickdown and shifts into/from 4th (OD) are bad for it. This means your top speed is somewhat limited to the rev limit in 3rd. This means on an otherwise stock setup you will be limited to about 120mph in 3rd. This might be ok for some, but not for others.
Future mods may also dictate what gearing is needed, aftermarket cams and bolt ons will allow you to raise the rev limiter and allower higher speeds in gear, a cam may require different gearing.
Your best bet is leave the rear alone until you know what you want. A stall would be a much better bet as it will help to overcome gearing due to a thing called shift extension and torque multiplication. I'd go for no less than a 3600rpm stall.
Also remember the stick Fbody rear is pretty weak, if you're serious it might be worth waiting until you upgrade the rear before you worry about gearing.
BTW - theres a link to gear calculator in my sig, you may find it helpful in deciding waht ratio is best for your setup/intentions.
